1.Field of the Invention
This invention relates to logarithmic amplifiers and, more specifically, to GaAs monolithic true logarithmic amplifiers.
2.Brief Description of the Prior Art
Prior art true logarithmic amplifiers are generally formed in silicon wafer and operate in the range of several hundred megahertz center frequency with a bandwidth of about 100 to 200 megahertz. Such prior art true logarithmic amplifiers have generally been composed of two circuit halves, each circuit half having a differential circuit pair per stage. The differential circuit pairs operate in parallel, one circuit pair having higher gain and a lower compression point and the other circuit having lower gain and a higher compression point. Together, these half circuits provide an amplifier response having a kink therein. It is desirable to utilize such true logarithmic amplifiers, however with the capability of operation at higher frequencies and/or with greater bandwidth.